A. Field of the Invention
The present invention relates to a suspended ceiling system for use in a cleanroom or other similar applications, and, more specifically, to a suspended ceiling system capable of supporting substantial loads either above or below the plane of the ceiling.
B. Description of the Related Prior Art
Precision manufacturing and assembly operations, particularly in the fields of semiconductors, aerospace, bioscience, pharmaceuticals, medicine, and food processing, are usually conducted in a controlled, contaminant-free work area, called a "cleanroom." A cleanroom is a specially constructed, enclosed area, environmentally controlled with respect to airborne particles, temperature, humidity, air flow patterns, etc.
A cleanroom conventionally includes a ceiling system for supply air and a raised floor system and/or side wall return air system. The ceiling system admits filtered air into the room, while the floor system or side wall grilles provide return air from the room in a closed loop arrangement. In some ceiling systems, a suspended framework supports air filters, blank panels, and lighting and defines an interior space between itself and the building structure to which it is attached. A supply duct or plenum provides temperature and humidity-conditioned air in the interstitial space above the framework. The air is delivered through filters to the room below.
In conventional cleanrooms, the utilities which sustain the manufacturing process are housed in separate "core areas" or above the ceiling. The utilities such as process piping, gases, air and vacuum lines are usually introduced into the cleanroom through openings in the walls or penetrations through the ceiling. Conventionally, a core area is disposed between two cleanrooms and thus provides utilities to both.
However, this conventional layout presents several problems. First, core areas occupy floor space which might otherwise be used as additional cleanroom space. Second, changing the size of a cleanroom is a cumbersome and costly ordeal which involves not merely relocating walls, but the removal and reinstallation of all of the utility equipment in an adjacent core area, especially when utilities and partitions penetrate the ceiling.
Conventional ceiling systems, however, are generally designed to support relatively light loads (e.g. air filters, blank panels, lights), typically on the order of a few pounds per square foot. Consequently, such systems are structurally unsuitable for bearing substantial loads such as process pipes, gas lines, air lines, vacuum lines, or a human technician who must service or repair equipment. Further, such ceiling systems are not suitable for directly supporting substantial loads suspended downward into the cleanroom. Finally, many conventional ceiling systems severely restrict where a rod or other suspension member may be attached to the framework for suspending it from the building structure.